Plants have developed intimate associations with different groups of fungal endophytes. In return for carbohydrates, these fungal endophytes help to improve the nutrient status and water balance of their host plant. In addition, they can protect the host plant against biotic and abiotic stresses, such as increased metal concentrations in the soil. Many endophytic fungi can survive at high concentrations of toxic metals, and can adapt to metal stress, which results in tolerant genotypes. Such fungi have developed many mechanisms that help them to maintain their metal homeostasis. These include passive mechanisms, such as metal binding to the cell wall, as well as active extracellular and intracellular chelation and transmembrane transport of metals. By restricting the uptake of toxic metals and improving the supply of essential elements to the host, fungal endophytes can ameliorate potential metal toxicity for their host plant. In this chapter, I discuss the effects of metal-enriched environments on the interactions between fungal endophytes and their host plants, along with the processes involved in the maintenance of metal homeostasis in fungi, and their ability to improve the fitness of plants in metal-enriched environments. |
